Software-defined networking (SDN) means a user-oriented network in which a user has control authority regardless of a basic network device such as a router or a switch, etc. and a separate software controller controls a flow of traffic.
In the SDN environment, a flow table including identification information of traffic flows and information for processing flows is managed. When actual user traffic is generated, a flow entry corresponding to the generated traffic is identified using the flow table, and a packet processing manner for the generated traffic is determined according to the identified flow entry.
The packet processing manners in the SDN environment may include traffic forwarding, traffic dropping, traffic modification, traffic queuing, etc.
The traffic forwarding is a function of outputting traffics through a specific output port, and the traffic dropping is a function of discarding traffics without outputting them through a specific output port. Also, the traffic modification is a function of modifying information of traffic headers such as virtual local area network (VLAN) tags, and the traffic queuing is a function of providing a Quality of Service (QoS) by scheduling traffics by using a queue in the traffic forwarding.
For QoS provisioning in a network apparatus such as a switch or router, there are basic QoS functions such as rate-limiting based on per-flow metering and enhanced QoS functions such as DiffServ utilizing queues for respective ports.
The network apparatus has a metering management table, manages the amount of packets for respective flows of the flow table by using the metering management table, and controls bandwidths for respective flows.
Also, the network apparatus can determine a manner of controlling a flow bandwidth such as rate-limiting, shaping, policing, etc., and restrict a bandwidth precisely by using minimum bandwidth information, maximum bandwidth information, etc.
In other words, QoS is provided through per-flow metering or per-port queues in the SDN environment, and traffic forwarding is processed according to a QoS policy configured for each flow or port.
However, since a method for managing multiple flows by using a single QoS policy is not available, there is a limitation that a unified bandwidth cannot be provided to multiple terminals and multiple services belonging to the same user.